LONG ARM
Provided is a long arm supported in a cantilever manner with light weight and high rigidity. The rod 30 is formed from rods 31-33 so as to be a multi-stage telescopic configuration. The rods 32, 33 respectively have upright columns 42, 43 on the tips. The wire 11 is suspended between the tip of the rod 31 and the lead end of the arm via the top of the column 42. The wire 12 is suspended between the base of the column 42 and the lead end of the arm via the top of the column 42. The wire 22 is suspended between the top of the column 42 and the lead end of the arm via the top of the column 43. The tension generation means 50 pulls the wires 10, 20. The air pressure generation means 60 applies pressure to the inside of the rod 30.
Latest HAKUSAN CORPORATION Patents:
The present invention relates to a long arm which is supported in a cantilever manner under gravity.
BACKGROUND ARTWhen handling an object at a short distance, for example, a manipulator having a long arm or a robot arm is used (Patent Literature 1). In a case of making a long arm with high rigidity for supporting its own weight, the arm comes to have an increased cross section or comes to be heavy in weight.
For example, when performing a remote control under a severe condition, there may be such a case where a control of electric system becomes difficult due to heat, an electromagnetic field, radiation dose, humidity, high concentration-toxic chemical substances, etc., under the environment. Further, there may be also a case where the control may be limited because of restrictions due to a requirement performance for explosion proof, a spatial limit, and the like. On the other hand, many of the conventional robot arms for industrial use are made by using standard parts and include a plurality of actuators for improving an operation efficiency. In this case, the robot arms sometimes cannot be used under such severe conditions because of sizes or specifications of the arms.
CITATION LIST Patent Literature[PATENT LITERATURE 1] JP 2003-89090A
SUMMARRY OF INVENTION Technical ProblemThe invention of the present application was made in view of the above-described background. The present invention provides an arm capable of suitably performing a remote control under severe conditions.
Further, a purpose of the invention of the present application is to provide a long arm which is light in weight, has high rigidity, and addresses a high safety.
Solution to ProblemThe present invention made to solve the above-described problem is directed to a long arm which is supported in a cantilever manner under gravity. The long arm includes rods for forming a long arm body, a plurality of upright columns standing from the rods, first wires stretched between a base section of the N - 1th upright column from an arm top end side and the corresponding arm terminal ends via a top section of the Nth upright column, second wires stretched between a top section of the N - 1th upright column from the arm top end side and the corresponding arm terminal ends via the top section of the Nth upright column, and tension generation means on the arm terminal end side for applying tension to the first wires and the second wires.
The tension of the first wires and the second wires on the arm top end side acts on to the arm on an arm terminal end side. The arm on the arm terminal end side is supported by the plurality of wires, which induces a coupled drive of wire. As a result, each of the wires can support the long arm with a relatively small traction force.
In the above-described invention, preferably, the rods have cross section areas which decrease from the arm terminal end side to the arm top end side.
In the above-described invention, preferably, the rods have cross section areas which decrease in a multistage manner from the arm terminal end side to the arm top end side. The plurality of upright columns is provided on stages of the rods in each corresponding manner.
In the above-described invention, preferably, the rods have an airtight property and receive a fluid pressure of a fluid supplied to the inside of the rods.
A rod shape and the internal pressure applied to the rods contribute to generation of an appropriate rod extension force that is to be generated by the fluid pressure at a posture of each of the upright columns of the rods. This enables to make the rods capable of supporting the long arm with the minimum rod weight.
In the above-described invention, preferably, the rods are formed in a multistage telescopic manner, i.e., the rods reduce their diameters from the arm terminal end side to the arm top end side. The rods formed into a multistage telescopic shape are extendable by the fluid pressure, and the plurality of upright columns is provided on stages of the rods in each corresponding manner.
The rods formed in a multistage telescopic manner are retractable, and thus are easy to carry in/out. Upon using, the rods extend out by the fluid pressure to form a rod.
In the above-described invention, preferably, the tension generation means can adjust the tension of the first wires and the second wires in accordance with the needed extension of the rods.
In the above-described invention, preferably, the tension generation means can adjust lengths of the first wires and the second wires in accordance with the needed extension of the rods.
The invention, preferably, includes third wires capable of controlling a feed and take-up speed, the third wires being stretched between the rods formed in a multistage telescopic manner and the corresponding arm terminal ends.
In the above-described invention, preferably, the third wires are provided to stages of the rods in each corresponding manner.
Accordingly, at the time of extending or at the time of retracting, the tension and the lengths of the first wires and the second wires can be adjusted.
Advantageous Effect of InventionThe long arm according to the invention of the present application is light in weight and has high rigidity. As a result, the invention addresses a safety. Further, the long arm according to the invention of the present application can be made longer than the conventionally used horizontal articulated type or vertical articulated type arms, and at the same time, can bear a larger loading capacity. Further, the long arm according to the invention of the present application can control the arm top end, i.e., can control a length and a rotation of the arm top end, even without using an electronic part at a position forming an articulate of the arm. Therefore, the long arm according to the invention of the present application is suitable for the use under severe environments where controlling of electric system is supposed to be difficult (i.e., is suitable for the use under the environments such as high temperature, high-dose radiation, strong electric field, and strong magnetic field in, for example, a thermal power plant and a nuclear power plant, under the environment requiring performance for explosion proof in, for example, plant facilities for oil/gas, and upon inspection of an inside of an aircraft fuel tank). Still further, the long arm according to the invention of the present application is also suitable for the use in checking bridges because a length of the arm is readily changed owing to the structure of the rods and the structure of the upright columns which connect the wires with the rods and the upright columns.
The long arm includes first wires 11, 12, 13, second wires 22, 23, rods 31, 32, 33, upright columns 42, 43, tension generation means 50, and air pressure generation means 60. Here, in the present specification, there are cases where the wires 11, 12, 13 are inclusively referred to as wire 10, and the wires 22, 23 are inclusively referred to as wire 20 for facilitating the explanation.
The long arm according to the invention of the present application is formed by connecting the rods 31, 32, 33 in this order from the arm top end side. The rods 31, 32, 33 have cross section areas which decrease in a multistage manner from the arm terminal end side to the arm top end side. As a result, the rod 31 can be inserted into the rod 32 and is slidable within the rod 32, and the rod 32 can be inserted into the rod 33 and is slidable within the rod 33. In the present invention, this is referred to as “in a multistage telescopic manner”. Further, in the present specification, there is a case where the rods 31, 32, 33 are inclusively referred to as rod 30.
In
The rod 30 has a hollow structure and an airtight property. To realize the airtight property, in the embodiment of the present invention, the rods 32, 33 each has a ring seal at its end.
The rod 30 may be made of any material. In view of a strength and lightness in weight, the rod 30 is preferably made of a carbon fiber reinforced plastic (CFRP).
The first wire 10 is stretched between a base section of the upright column on the arm top end side and the arm terminal end via a top section of the neighboring upright column on the arm terminal end side. For example, the wire 11 is fixed to a top end of the rod 31 and is stretched between the top end of the rod 31 and the corresponding arm terminal end via a pulley provided on a top section of the upright column 42. The wire 12 is suspended around a pulley provided on a base section of the upright column 42 and is stretched between the pulley of the base section of the upright column 42 and the corresponding arm terminal end via a pulley provided on the top section of the upright column 43. The wire 13 is suspended around a pulley provided on a base section of the upright column 43 and is stretched between the pulley of the base section of the upright column 43 and the corresponding arm terminal end via a pulley provided on a top section on the arm terminal end side. In the invention of the present application, if a pulley is provided also on the base section of the upright column on the arm top end side, if a wire is suspended around the top section of the neighboring upright column on the arm terminal end side, and if the wire is stretched between the base section of the upright column on the arm top end side and the corresponding arm terminal end via t the pulley provided on the base section of the upright column on the arm top end side and the pulley provided on the base section of the upright column on the arm top end side, the wire tension can be increased only therebetween owing to the effect of movable pulleys. Such structure is preferable. The following structure is also preferred. Namely, a plurality of pulleys is provided on each of the base section of the upright column on the arm top end side and the top section of the neighboring upright column on the arm terminal end side, and wires are also stretched between the plurality of pulleys, thereby increasing the wire tension. At the time, the wires may be suspended whichever of the base section of the upright column on the arm top end side or the top section of the neighboring upright column on the arm terminal end side.
The second wire 20 is stretched between the top section of the upright column on the arm top end side and the arm terminal end via the top section of the neighboring upright column on the arm terminal end side. For example, the wire 22 is suspended around the top section of the upright column 42 and is stretched between the top section of the upright column 42 and the corresponding arm terminal end via the pulley provided on the top section of the upright column 43. The wire 23 is suspended around the top section of the upright column 43 and is stretched between the top section of the upright column 43 and the corresponding arm terminal end. If a pulley is provided also on the top section of the upright column on the arm top end side, if a wire is suspended around the top section of the neighboring upright column on the arm terminal end side, and if the wire is stretched between the top section of the upright column on the arm top end side and the corresponding arm terminal end via the pulley provided on the top section of the upright column on the arm top end side and the pulley provided on the base section of the upright column on the arm top end side, wire tension can be increased only therebetween owing to the effect of the moving pulley. Such structure is preferable. The following structure is also preferred. A plurality of pulleys is provided on each of the top section of the upright column on the arm top end side and the top section of the neighboring upright column on the arm terminal end side, and a wire is stretched between also the plurality of pulleys to increase the wire tension more. At the time, the wire may be suspended around whichever of the top section of the upright column on the arm top end side or the top section of the neighboring upright column on the arm terminal end side.
The tension generation means 50 is provided on the base structure on the arm terminal end side to hold ends of the wires 11, 12, 13 and the wires 22, 23 and to pull the wires, thereby applying the tension to each wire. More specifically, the most suitable tension is applied by a motor which serves to pull the wires 11, 12, 13 and the wires 22, 23.
The most suitable tension and the most suitable lengths of the wires 11, 12, 13 and the wires 22, 23 can be calculated based on the principle of the present application (will be described below) with ease. Further, a control may be performed at the same time by providing various types of sensors or a camera for monitoring a rod position.
The upright column 42 is composed of a right upright column and a left upright column standing from the top end of the rod 32. The upright column 43 is composed of a right upright column and a left upright column standing from the top end of the rod 33. A pulley 46 is provided on the base section of the upright column 43. A pulley 47 is provided on the top section of the upright column 43. Similarly, the upright column 42 may also include pulleys on the base section and the top section thereof. The two upright columns, i.e., the right upright column and the left upright column, are connected by a frame beam. Then, the frame beam serves as a suspension end where ends of the parallelly stretched wires over the arm and ends of the obliquely stretched wires are suspended. Further, the frame beam functions as also a guide of the wires stretched from the arm top end side to the frame beam itself. An embodiment illustrated in
The rods are extendable/retractable.
The rod 30 in the retraction state is caused to be extended by the air pressure generation means 60. The rod 31 projects out from the rod 32, the rod 32 projects out from the rod 33, and the rod 33 projects out from the base structure. In the invention of the present application, the air pressure generation means 60 may be any conventionally used means.
The rods according to the invention of the present application, as shown in
The principle of the invention of the present application will be described below with reference to a simple model.
A wire b1 is stretched between the point A and the top section of the upright column at the point B, and the wire b1 is further stretched to the corresponding arm terminal end. Between the top section of the upright column at the point B and the top section of the upright column at the point C, a wire a2 is stretched, and the wire a2 is further stretched to the corresponding arm terminal end. Further, between the point B and the top section of the upright column at the point C, a wire b2 is stretched, and the wire b2 is further stretched to the corresponding arm terminal end.
Referring to
Firstly, Fb1 is decided based on a balancing condition in a vertical direction at the point A.
Nextly, Fc1 is decided based on a balancing condition in a horizontal direction at the point A.
Then, an air pressure P is decided based on the following conditional expression in which the extension force by the air pressure and the Fc1 balance. Here, an internal radius r1 of the first rod may be given any proper value considering the intended use of the rod.
Fc1 = PA1 = Pπr12
Referring to
In
Fa2 is decided based on the moment balance, i.e., w21 = Fa2h, around the point B. The calculation of Fa2 in this manner means that the arm position can be kept even when a support moment is zero at the upright column at the point B.
Nextly, Fb2 is decided based on a balancing condition in a vertical direction at the point B.
Nextly, Fc2 is decided based on a balancing condition in a horizontal direction at the point B.
Then, based on a condition, i.e., Fc2 = PA2 = Pπr22, for generating a desired extension force by the above acquired air pressure P, a cross section area A2 and a radius r2 of the internal diameter of the rod are decided.
Here, the area of the end surface of the second rod on the arm terminal end side is acquired by A2 - A1. The air pressure pushing the end surface of the first rod on the arm terminal end side acts on also the end surface of the second rod on the arm terminal end side. Namely, the air pressure of P(A2 - A1) + PA1 = PA2 acts thereon. The inventor named this phenomenon a coupled drive of air pressure.
In the cantilevered beam, a moment becomes larger from the top end to the terminal end of the beam. Further, in a case where the arm is formed in a multistage manner, the cross section becomes larger and the self-weight increases from the top end to the terminal end. This structure generates larger moment. As a result, the axial force becomes larger from the top end to the terminal end in accordance with the increasing moment.
To the contrary, in the coupled drive of the air pressure, pressure of the supplied compressed air does not change. But, because the cross section area becomes larger, a larger extension force by the air pressure is applied as it goes from the top end to the terminal end. As a result, by deriving an appropriate value of the cross section area of each rod according to the above-described calculation process, the extension force by air pressure which should be applied to each rod can be generated with the minimum required self-weight, resulting in opposing the moment.
Referring to
The wire b1 receives tension Fb1. Here, in a case where the wire b1 is stretched in double between the point A and the top section of the upright column at the point B, the tension applied to each wire between the top section of the upright column at the point B and the corresponding arm terminal end is Fb1/2 based on the principle of the running pulley. Further, because the wire b1 is composed of two wires, i.e., a left wire and a right wire, the tension applied to each wire is Fb1/4.
The wire b2 receives tension Fb2. Further, the wire b2 is composed of two wires, i.e., a left wire and a right wire, and each wire receives tension of Fb2/2 (see,
In
As described above, the long arm can be realized with a relatively small wire traction force and a relatively small air pressure. Further, because the rods used here are hollow, light weight can be achieved.
In the long arm of the invention of the present application, the wire over the rod receives only a tensile force, and the rod beneath the wire receives only a compression force. Therefore, a moment applied to the base section of the upright column is zero. As described above, the upright column is provided on the top end of each rod of the air pressure-extending type telescopic rod to which compressed air is supplied, and wires are stretched between the upright columns to support the long arm by using the traction force of the wires which supports a shearing force and a bending moment as well as to cause the rod to extend/retract. It becomes clear that an introduction of such truss structure enables designing of a practical arm satisfying the above-described specification. The inventor named this cantilever arm of the present application a truss arm.
Here, the truss structure is a structure formed by connecting triangle-shaped structures and has such a feature that each joint receives only a tensile force and a compression force, but no bending moment occurs in each member. Therefore, the truss structure is advantageous in constructing a large structure. In the standard truss structure, an X-shaped frame in which obliquely paired corners of the four corners of a square frame are connected is mounted. On the other hand, the long arm of the invention of the present application is an arm which is caused to extend in a horizontal direction in a cantilever manner and has such an operation condition that only a downward load is constantly applied to the arm top end. Therefore, the present invention employs a telescopic rod which is extendable by air pressure as a downward structure which receives only a compressive stress, the left and right upright columns are provided on the ends of all the rods having different diameters of the telescopic rod, and a wire is stretched between the paired obliquely-crossing corners of the X-shaped frame where a traction force is generated. Namely, the invention of the present application employs a truss structure which is different from the conventional truss structure.
In the meantime, in the present application, where the rods are made hollow to receive air pressure inside thereof, the air pressure contributes to generation of forces in an axis direction and in a radial direction of the rods. The pressure in the radial direction which attempts to inflate the diameters of the rods is supported by a strength of the members of the rods. As a result, the axial force is applied to only the rods extendable in the axis direction and supports the compression force applied from the outside. With the structure, because the compression force is not applied to the members of the rods themselves, such an effect that buckling unavoidable for the long arm does not occur is produced.
Where the rod 30 is extended by the air pressure, any rod which extends faster than other rods is restricted by the feed and take-up speed controlling means 70, and thus the rod 31, the rod 32, and the rod 33 extend at the same rate.
As described in the above principle, the invention of the present application is characterized in that the coupled drive of the wires and the coupled drive of the air pressure are linked together while keeping the balance therebetween.
A control of the extending speed contributes to the adjustment of the wire traction force and the wire length to appropriate values while the rod is extending.
The present invention is not limited to the above-described embodiments, but various modifications thereof may be also embraced within the scope of the present invention. For example, the number of rods, wires, and upright columns may be any number.
In
The rod position can be controlled by adjusting lengths of the wires while controlling the tension of the wires. For example, as shown in
Referring to
Further, the long arm according to the invention of the present application can keep the tension by means of, for example, a selection of materials for the hollow rods and the wires. This can realize the lightness in weight.
In the invention of the present application, it is also possible to make a balance between the tension of the wires and the weight of the rods. This makes it possible to appropriately design a diameter and a length in such a manner that the arm does not contact an introducing location and obstacles inside the industrial complex.
In the invention of the present application, when inconvenience, e.g., twisting of the arm, occurs in the arm, the inconvenience can be fixed by adjusting each respective wire (especially, by adjusting the balance between a right wire and a left wire). With the structure, the arm position can be kept.
REFERENCE CHARACTER LIST
- 10, 11, 12, 13 first wire
- 20, 22, 23 second wire
- 30, 31, 32, 33 rod
- 36 rotation shaft
- 37 air pressure transmitter
- 40, 42, 43 upright column
- 46, 47 pulley
- 50 tension generation means
- 60 air pressure generation means
- 70 take-up speed controlling means
- 80, 81, 82, 83 third wire
Claims
1. A long arm supported in a cantilever manner under gravity, the arm comprising:
- rods for forming a long arm body;
- a plurality of upright columns standing from the rods;
- first wires stretched between a base section of the N - 1th upright column from an arm top end side and the corresponding arm terminal ends via a top section of the Nth upright column;
- second wires stretched between a top section of the N-1th upright column from the arm top end side and the corresponding arm terminal ends via the top section of the Nth upright column; and
- tension generation means on the arm terminal end side for applying tension to the first wires and the second wires.
2. The long arm according to claim 1, wherein the rods have cross section areas which decrease from the arm terminal end side to the arm top end side.
3. The long arm according to claim 1:
- wherein the cross section areas of the rods decrease in a multistage manner from the arm terminal end side to the arm top end side; and
- wherein the plurality of upright columns is provided on stages of the rods in each corresponding manner.
4. The long arm according to claim 1, wherein the rods have an airtight property and receive a fluid pressure of a fluid supplied to the inside thereof.
5. The long arm according to claim 4:
- wherein the rods are formed in a multistage telescopic manner such that the rods reduce their diameters from the arm terminal end side to the arm top end side;
- wherein the rods which are formed in a multistage telescopic manner are extendable by the fluid pressure; and
- wherein the plurality of upright columns is provided on the stages of the rods in each corresponding manner.
6. The long arm according to claim 5, wherein the tension generation means is configured to adjust tension of the first wires and the second wires in accordance with the needed extension of the rods.
7. The long arm according to claim 5, wherein the tension generation means is configured to adjust lengths of the first wires and the second wires in accordance with the needed extension of the rods.
8. The long arm according to claim 5, further comprising third wires for controlling a feed and take-up speed, the third wires being stretched between the rods formed in a multistage telescopic manner and the corresponding arm terminal ends.
9. The long arm according to claim 8, wherein the third wires are provided to the stages of the rods in each corresponding manner.
Type: Application
Filed: Jul 22, 2020
Publication Date: Sep 7, 2023
Applicant: HAKUSAN CORPORATION (Tokyo)
Inventor: Shigeo HIROSE (Tokyo)
Application Number: 18/005,956